1. Field of the Invention
The present invention relates to a flux cored wire, and more particularly to a flux cored wire for gas-shielded arc welding, made of metal such as titanium(Ti), silicon(Si) a magnesium(Mg) potassium(K), sodium(Na) or oxide thereof, in which a flux satisfying a specific component relationship of K2O, Na2O and SiO2 is filled in a metal sheath, and having a superior wearability in the welding of a mild steel and a high tensile strength steel.
2. Discussion of the Related Art
Generally, arc welding mainly used in welding metal applies a power of a low voltage and a high current between a welding material (i.e., an electrode or a filler metal) and a base metal to thereby generate an arc heat. The generated arc heat allows both of the welding material and the base metal to be melted and welded to each other. Arc welding is largely classified into two ways. One is a consumable electrode type arc welding and employs an filler metal as an electrode. In the consumable electrode type arc welding, filler metal and a base metal are both melted by arc heat generated between the base metal and the welding electrode to form a bead at a welding point. There are a shielded metal arc welding coated electrode arc welding, a submerged arc welding, and a metal active gas arc welding and metal innert gas arc welding as kinds of the arc welding.
The other is a non-consumable electrode type arc welding. In the non-consumable electrode type arc welding, the electrode functions only to generate an arc. Therefore, to obtain a welding metal, a filler metal should be added within an occurrence range of an arc and be melted. There are a TIG (Tungsten Inert Gas) welding and an atomic hydrogen welding as kinds of the electrode-non-molten type arc welding.
The remaining arc welding methods except the shielded metal arc welding supply an inert gas or carbon dioxide gas around a molten pool where a liquid metal molten by arc heat during welding is formed to prevent oxidation of the molten pool or control an atmosphere of a melted metal, and shield a contact of the melted metal with air. To this end, they are called as gas-shielded arc welding.
Gas-shielded arc welding is largely classified into two ways, one using an inert gas like MIG(Metal Inert Gas) or TIG welding and the other using carbon dioxide gas which is cheap in cost. For these two welding methods, solid wire and flux wire are used as welding material.
When the welding material is not used for a specific purpose, it has preferably a bead shape. In these days, due to the coatability and removability of slag and a fast rate of deposition, the flux cored wire is increasingly used.
The flux cored wire is used as a welding material for the gas-shileded arc welding having a high efficiency in the fields of automobile, shipbuilding, architecture, etc. The flux cored wire includes a metal sheath and a flux filled in the metal sheath. Since the flux cored wire has a superior workability and stability for welding, it has advantages in that an occurrence amount of spatter is small and a uniform bead is obtained.
For high efficiency of the gas-shielded arc welding, it may be required to increase the welding speed by 50% or more in a downward or a horizontal fillet welding. To obtain such a target welding speed, a grain distribution of main composition in the flux cored wire is controlled or a composition ratio of a slag forming agent is controlled.
However, these trials show only improved appearance of the bead rather than increase in the welding speed.
As one method for increasing the welding speed, there is a method using plural welding electrodes. This method, however, makes the welding instrument and peripheral instrument complicated, and thereby it has a drawback in that an investment cost for the welding instrument increases.
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the present invention is to provide a flux cored wire for gas-shielded arc welding having a superior welding capability in all welding position, especially a convenience in the vertical upward welding, and a superior bead shape, and simultaneously making it possible to perform a horizontal fillet welding in a high speed.
Additional features and advantages of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the followings or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained as particularly pointed out in the appended claims.
To achieve the object and in accordance with the purpose of the present invention, as embodied and broadly described, a flux cored wire for gas-shielded arc welding comprises a Ti and a Ti oxide of 3.0 wt % to 8.0 wt % as calculated in terms of TiO2 content, a Si and a Si oxide of 0.5 wt % to 2.0 wt % as calculated in terms of SiO2 content, a metal Mn and an alloy of Mn of 1.5 wt % to 3.5 wt % as calculated in terms of Mn content, a carbon(C) of 0.02 wt % to 0.10 wt %, an Mg and an Mg oxide of 0.5 wt % to 1.5 wt % as calculated in terms of MgO content, a compound of Na2O and K2O of 0.2 wt % and less, a Zr and a Zr oxide of 0.1 wt % to 0.5 wt % as calculated in terms of ZrO2 content, and an Al and an Al oxide of 0.2 wt % to 0.8 wt % as calculated in terms of Al2O3 content, wherein the composition ratio of the above described components is defined with respect to a total weight including a metal sheath which is a crust and satisfies the following formulas (1) and (2).                     0.1        ≤                                            2              ⁢                              xe2x80x83                            ⁢                              K                2                            ⁢              O                        +                                          Na                2                            ⁢              O                                            SiO            2                          ≤        0.3                            Formula        ⁢                  xe2x80x83                ⁢                  (          1          )                                        1.6        ≤                              FeO            +            MnO            +            MgO                                              SiO              2                        +                                          Al                2                            ⁢                              O                3                                      +                          0.4              ⁢                              xe2x80x83                            ⁢                              TiO                2                                                    ≤        2.1                            Formula        ⁢                  xe2x80x83                ⁢                  (          2          )                    